Solid state drives (SSDs) may significantly improve input/output performance of computer systems. SSDs may be built using multilevel cell (MLC) NAND in which each memory cell of an array may have at least four states, capable of storing at least two bits of data. In a writing operation in an MLC NAND, data for a lower page may be written and, subsequently, data for an upper page, which corresponds with the lower page, may be written. Lower-page corruption may occur when a power failure happens while data from the corresponding upper page is being written into the cells.
Some SSDs include additional power-fail protection circuitry, composed of power control logic as well as capacitors to store power. However, this solution may be associated with both cost and space required for the power-fail protection circuitry.